If you've ever worried that raising your child in two languages might slow down their speech, you've absorbed a myth that's been circulating for decades — and it's simply not true.
I sat down with Joanne Cazeau, M.S., CCC-SLP, a bilingual pediatric speech-language pathologist and founder of Koze Speech Therapy in New Jersey, to get real answers: what bilingualism actually looks like in early childhood, what's a genuine red flag versus totally normal, and what to actually do at home to support it — without turning play into a lesson.
What counts as "bilingual" in early childhood?
Bilingualism simply means a child is learning and using two languages; multilingualism means more than two. In early childhood, that shows up as a child understanding a word and being able to use it themselves, across different contexts — not textbook fluency, just functional use.
Does raising a bilingual baby cause speech delays?
No. Joanne was direct about this: it's a myth that's been repeated for generations, born from a decades-old piece of research that was misinterpreted and never corrected once it became conventional wisdom — passed down by well-meaning pediatricians and relatives ever since. Bilingualism does not cause language delays.
Code-switching is a skill, not confusion
When a bilingual child mixes languages mid-sentence, that's not a sign they're mixed up — it's a sign they're paying attention. Children (and adults) reliably code-switch based on who they're talking to: a bilingual child won't drop Spanish words into a conversation with someone who only speaks English. Recognizing who has access to which language is a genuinely sophisticated cognitive skill, not a gap.
How to actually count a bilingual child's vocabulary
A bilingual toddler can look "behind" if you only count words in one language. Joanne's fix: count total vocabulary — every word a child has across every language they're learning. A two-year-old who says "cat" and "gato," "dog" and "perro," has four words, not two. If a family only counts the English side, the child can look delayed when they're actually right on pace once every language is included.
Bilingual milestones by age: what's typical vs. a red flag
Bilingual and monolingual children follow the same general developmental path — nothing about being raised in two languages should look drastically different on the surface. Joanne's benchmarks, counting words across all of a child's languages combined:
AGE & WHAT TO LOOK FOR
- 6 months: Simple babbling has started
- 9 months: Repeated babbling ("ba-ba-ba," "da-da-da")
- 12–13 months: First word, said spontaneously (not prompted) and consistently
- 18 months: At least 10 words; understands simple directions and words like "no" or "stop"
- 24 months: At least 50 words total; answers simple questions; follows 1–2 step directions
Mixing languages, or not pronouncing a word exactly the way an adult would, is not a red flag on its own. What's worth a conversation with a specialist: a child not meeting the milestones above, not responding to their name, or not showing typical play and social engagement with others.
For milestone tracking, Joanne points families to ASHA (the American Speech-Language-Hearing Association), Zero to Three, and Pathways.org — not the CDC's most recent milestone chart, which was released without speech-language pathologist input and isn't one most SLPs currently rely on.
How to raise a bilingual baby without adding extra work
Joanne's core philosophy: language builds through everyday routines and connection, not curriculum. Under age five especially, learning should feel like play, not work. A few ways that looks in practice:
- Narrate routines you're already doing — name ingredients while cooking, sing a lullaby in your target language at bedtime
- Anchor one simple phrase to one activity — "up, up, up" during play, "hola" during peekaboo — rather than trying to introduce a lot at once
- Go easy on flashcards — Joanne isn't against them, but flat, repeated drilling doesn't always transfer: a child can say "vaca" to a flashcard all day and still not connect it to a real cow at the farm. If you use them, bring them into real moments instead of isolated drilling.
Finding real books in the target language
One thing Joanne and I agreed on without hesitation: finding genuinely bilingual books, or books actually written in a target language, is harder than it should be. A story conceived and written in Spanish by a Spanish-language author carries nuance a direct English-to-Spanish translation often loses — translation is rarely one-to-one. It takes more digging to find books published by presses in the language's country of origin, but the depth is worth the extra effort.
Frequently asked questions
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Does raising a child bilingual cause speech delays?
- No. This is a long-standing myth, not a research-backed finding. Bilingual and monolingual children follow the same general developmental path.
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Is it normal for a bilingual toddler to mix languages?
- Yes. Code-switching is a sign a child understands both languages and is tracking who they can use each one with — it's a cognitive strength, not confusion.
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How do you count vocabulary for a bilingual child?
- Count total vocabulary — every word across every language a child is learning. A child who says both "cat" and "gato" has two words, not one.
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Do I need to be fluent to raise my child bilingual?
- No. Share whatever you have — words, songs, phrases from a grandparent. Children can build on a foundation later; the goal is exposure and connection, not a parent's fluency.
Joanne's closing message for parents who feel like they're falling short: it doesn't have to look perfect, especially before age five. If it feels hard, that's worth a second look at expectations — not a sign to give up. Use your target language the same way you already use English: talk, sing, play, and read together. That's the whole formula. And if you want more support, Birdsong's own research collaborator, Dr. Taylor Benyahia — a bilingualism researcher who's also raising a bilingual toddler herself — is exactly the kind of expert Joanne recommends families lean on.
"Bilingualism is a gift. No matter how you're doing it, no matter what the journey looks like right now, you're doing something that will benefit your child for decades. It really ties them into their culture and identity — that's a bond you can't break."
Joanne Cazeau, M.S. CCC-SLP
ABOUT JOANNE
Joanne W. Cazeau, M.S., CCC-SLP, is a bilingual, New Jersey-licensed pediatric speech-language pathologist and founder of Koze Speech Therapy, where she supports late talkers and toddlers through play-based, child-led therapy. She's also the creator of Beyond Babbles, where she shares research-backed strategies for parents of babies and toddlers, and supports multilingual families around the world through virtual consultations.